Well, yeah, nothing makes your wizard look awesome than someone else's non-caster being a sidekick. Moreover, D&D has actively cultivated this mentality, which is why it's more common in older players who gripe about powerful martials being too anime. Anyone who wanted a better caster/.non-caster balance played other systems. Gygax voiced that the "serious" players graduated to magic-users, so them being a cruddy training wheels class was intended. The triumph of the nerd over the jock and caster supremacy were baked in.
Pretty much, yes. 3.5's Tome of Battle, and all of 4e, was designed to make "non-magical" classes ("Martial" has become a loaded term, IMO) more balanced against their magic-using allies. But a very vocal part of the D&D community rejected these ideas, wanting Fighters to be guys with no special abilities other than "hit stuff good" "have lots of hit points" and "wear heavy armor".
Meanwhile, 5e's Wizards are superior to 3e's Wizards in most respects. They have more staying power, can wear armor if they want to, have cantrips that actually do more than d3 damage (and are usable at will, as opposed to 6x per day) and have actual class abilities beyond "a few free Feats and spells".
They have less high level spell slots, and obviously caster level > upcasting...but at the same time, save DC's being set by your level and not what spell you are using is pretty potent, so that's about a wash. And not having to play the Spell Resistance minigame is good too.
Many spells are stronger at base level as well. No d4+1 single magic missile or 5d6 fireballs here!
Concentration mostly just changes what spells are being used, I've found. Which, sadly, includes buff spells that you'd like them to be casting on their poor fighting man allies. "Sorry Fighter, can't spare the concentration to give you Haste, I have a Sleet Storm I need to keep up so those Bugbears can't reinforce the Hobgoblins for a turn or two."